Re: [TCML] SRSG Power factor & Res Charging Freq

[futuret@xxxxxxx]

Phil,

The power factor depends a lot on the adjustment of the ballast.
By varying the ballast setting, it will make the power factor either
better or worse.  At 120 bps (100 for the UK), I was able to obtain
an excellent power factor by adjusting the ballast correctly for the
particular transformer and capacitor.  I didn't use any math, but I
measured the power factor by comparing VA and watts, using
both a true wattmeter and an ammeter and voltmeter.  If I
remember correctly, the phasing of the rotary affects the power
factor also.  It's possible to phase the rotary differently, then
adjust the ballast to obtain the same spark length.  The watts
drawn will remain the same, but the power factor will get worse.
So basically one has to adjust both the rotary phase setting and
the ballast setting to obtain the best power factor at 120 (100)
bps.  I posted the results of the tests I did in this area many years
ago on this list.  In general I've noticed there are many
misunderstandings in this area, and also in the area of LTR, STR, and
resonant cap values, for various transformers.  Basically it's all 
affected
by the ballast.  Of course with NST's the "ballasting" is fixed so it's
a different story.

Cheers,
John


-----Original Message-----
From: Phil Tuck <phil@xxxxxxxxxxx>
To: Tesla@xxxxxxxxxx
Sent: Fri, Jul 3, 2009 5:51 am
Subject: [TCML] SRSG Power factor & Res Charging Freq



Hello.

I am in the process of building a SRSG and looked into the effect of 
Power
Factor and bps rates. Richie's site has an informative  graph showing 
the
effect of resonant charging figures against expected power factors and
differing bps rates. In my case my resonant charging figure of 78hz (see
footnote) with a bps of 100 would give me a PF of 0.2 (see 2nd graph 
down at
http://www.richieburnett.co.uk/external.html ) This is truly horrible! 
How
much increase on total current drawn that this will cause is something I
have not worked out.

A 200 bps will give me a more respectable  0.9 however.

Personally I favour 100 bps after reading countless posts on the subject
over the last few days, but it looks increasingly like I will have to 
accept
200bps. There are so many differing results and posts favouring  either 
100
or 200 (120 or 240) that that question will be debated for a long time.

As the general method of PF correction seems to be of the 'try it and 
see'
type, is the PF figure of 0.2 so bad that the amount of PF correction 
with
caps would most likely be so large as not to be feasible? (Or hopefully 
my
maths are all wrong)



Footnotes:



Cap = 72nF Sec I = 0.675A @ 12100v



Sec Z = 12100/0.675 = 17926 ohms



17926 = 2*pi*F*L     L=17926/314.159 = 57.06H secondary inductance



Charging Freq =1/ (2*pi* SQR(57.06 * 0.000000072)) = 78hz





Also Richie graph shows 120 bps, while all the other plots are based on 
50hz
multiples. As Richie is UK I assume this is a typo. Either way it looks 
bad
for 100 bps @ 78hz Charge F res



Regards



Phil

www.hvtesla.com











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